Climate and Weather

The study attempts to develop a computerized model for Geomorphological Instantaneous Unit Hydrograph (GIUH) for estimation of flood hydrographs resulting from intermittent storms of varying intensity. The model applied to the rainfall-runoff data of the Myntdu-Leska basin of Meghalaya infers that the channel network and geomorphological features are closely related to the retention and discharge characteristics of the basin.

The theory of GIUH assumes that rainfall that occurs over a basin is assumed to be composed of infinite number of non-interacting drops of uniform size. After spending some time in one state in the channel or overland region, the drop makes transitions to another state to reach the basin outlet. Assuming one parameter, exponential time distribution of one drop chosen at random from the basin defines the IUH of the basin.

The study estimates the average soil loss using the Geographic Information Systems (GIS) tool of Integrated Land and Water Information Systems (ILWIS) and the Universal Soil Loss Equation (USLE) methodology for the Hire nadi catchment, in Yelbarga taluk, Koppal district of Karnataka, under different conditions.  

Scientific planning for soil conservation and water management requires knowledge of the relations among factors that cause and prevent soil and water loss.  Controlled studies on field plots and small watersheds have supplied vital information regarding these complex factors and their interrelations.

The study assesses waterlogging in a canal command area in Rohtak and Jhajjhar districts through waterlogging area zonation using multi-spectral and multi-temporal imagery like IRS LISS III data of pre and post monsoon period. Seasonal and permanent waterlogged area and standing water were delineated on the basis of remote sensing data, digital elevation model and groundwater data.

The study estimates the snow cover area for four major basins in the Himalayan region viz. Chenab up to Akhnoor, Ganga up to Devprayag, Satluj up to Bhakra and Beas up to Pandoh using IRS - IC and ID WiFS data. Snow cover estimation was done for the years 1997-2000 using image processing system ERDAS Imagine. The maximum and minimum snow cover extent for the month of September-October and March-April were delineated and on the basis of these the depletion curves for each basin was made for the four years. This output is useful for carrying out snowmelt runoff modeling.

The study aims to determine the climatological water balance of Krishnai river basin in Goalpura, Assam using the popular Thornthwaite’s concept of Potential Evapotranspiration (PET) to calculate the availability of water for various uses. The method offers a firm basis for appraising the problems related to water development projects in the planning stage and provides a sound footing for operating and managing the system. 

The study applies advanced models of design storm like Flood Analysis and Protection Systems (FLAPS) and HEC-1 for rainfall-runoff simulation employing selected short-term events of three basins of the north-eastern region – Myntdu-Leska (Meghalaya), Krishnai and Dudhnai (Assam). The results are used to study the sensitivity of the model parameters with respect to different hydrological parameters of the basin. The performance of these methods is evaluated by analyzing the isolated events. An attempt has been made to evaluate the non-linearity in rainfall-runoff response, using a simple storage-runoff dynamic model. The relationship of incipient soil moisture and transmissivity with direct runoff and recharge is studied.

The study uses remote sensing data to develop a land use classification and applies statistical methods appropriate for Indian catchments to estimate the annual sediment load from the Upper Indravati catchment in Orissa for the year 2000. The study points to the fact that assessment of reservoir catchment regions at regular intervals would enhance the understanding of the geodynamic processes and help in identifying effective control measures.

The study is based on investigations and collection of necessary information on the super cyclone in Orissa in October 1999. It examines cyclonic phenomenon in the country in general and Orissa in particular, and stresses the need for preparing a comprehensive plan for dealing with such disasters.

A widespread view that is gaining ground is that climate related migration could evolve into a global crisis by displacing a large number of people from their homes and forcing them to flee. Christian Aid postulates that a billion people could be permanently displaced by climate change related phenomenon such as droughts, floods and hurricanes (Christian Aid 2007). The fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC) mentioned the “potential for population migration” due to increase in the number of areas affected by droughts and an increase in the intense tropical cyclones activities (IPCC 2007: 18). In particular, it seems likely that significant numbers of people will be displaced, either temporarily or permanently, from their homes as a consequence of global warming (Stern 2006). Available scientific evidences indicate that a large number of people might be displaced due to climate change. However, much of the literature on this issue refers to the question of whether the   people forced to migrate as a consequence of climate change should be described as climate refugees. There is no internationally agreed definition of the term “climate refugee” and the extent to which these displaced persons constitute a separate identifiable group. Although it is now widely recognised that climate change will significantly adversely affect India, there are few studies available on how climate change is going to affect the migration of people. It has been asserted that 70,000 people out of the 4.1 million living in the Indian part of the Sundarbans islands would be rendered homeless by 2020 (EPW, 6 June 2009).

Climate change has been denied, labelled as a  myth and a political manoeuvre or synergised with individual weather events.